The Siemens SIRIUS 3UG4624-2CS20 is a residual current monitoring relay with digital setting, designed for three-phase supplies. It measures residual currents from 30 mA up to 40 A AC, making it suitable for ground-fault detection on motor feeders, distribution boards, and industrial loads where early leakage warning is required. Rated voltage spans 90 to 690 V AC at 50/60 Hz, covering standard low-voltage networks up to 690 V line-to-line. The relay operates across -25 to +60 °C ambient and stores at -40 to +85 °C, which is typical for panel-mounted protection devices in unconditioned enclosures. The unit is rated IP20, meaning it is touch-safe but not sealed against moisture — install inside a suitable enclosure. Mounting is via screw or snap-on onto a 35 mm standard mounting rail; the 22.5 mm width (one DIN module) conserves panel space. Mounting position is any, which simplifies layout in retrofit panels.
Key Ratings and What They Mean for Fit
The measurable current range of 30 mA to 40 A AC is the core selection parameter. The lower threshold (30 mA) meets the typical sensitivity for personnel protection per IEC 60364, while the upper end (40 A) covers large feeder leakage. The digital setting allows step-less adjustment within this span, so one relay covers multiple branch sizes without stocking different models. Rated insulation voltage of 690 V AC confirms the relay can be connected directly to 400/480 V three-phase systems with margin. The output contacts are rated: 3 A at 250 V AC, 3 A at 400 V AC, 1 A at 24 V DC, 0.2 A at 125 V DC, and 0.1 A at 250 V DC. These ratings govern the load the relay can switch — typically a PLC input or a contactor coil — not the monitored circuit current. The relay includes an error memory function and external reset capability, which means it can latch on fault and be reset remotely — useful for unmanned substations or remote panels where manual reset is impractical.
Lifecycle and Sourcing Reality
The relay carries the SIRIUS brand, Siemens' modular industrial controls platform. Compliance documentation — RoHS, REACH, and relevant IEC/EN standards — is provided with the unit. The protection class IP20 and degree of pollution 3 rating are per IEC 60947-1, suitable for industrial environments with conductive pollution.
Mounting and Integration Notes
Fastening is by screw or snap-on onto a 35 mm standard mounting rail per EN 60715. The 22.5 mm width occupies one DIN module. Clearances: 0 mm upwards, forwards, backwards, downwards, and at the side — meaning zero spacing is required between adjacent devices, though practical wiring access may dictate some gap. Terminals accept solid or stranded conductors of 24 to 16 AWG (2x per clamp). The relay is designed for three-phase supplies; connect the monitored lines and the neutral (if required) per the wiring diagram. The output is a changeover contact rated as above.